The invention relates to a nozzle arrangement, a nozzle holder and a device for extruding dough materials using the nozzle holder.
Baking articles, doughs and confectionery are often extruded by squeezing material under pressure through a nozzle arrangement to form a strand. As such, the strand may be carried away by a conveyor belt or cut into short sections. The outer shape of the strand, in particular its circumferential shape, is dependent upon the nozzle arrangement.
A nozzle arrangement is known from EP-A-0 704 158 with an inner stationary nozzle, which is enclosed by two outer nozzles rotatably mounted in a rotor. The inner nozzle extends in the direction of flow beyond the mouth of the outer nozzle or is extended beyond said mouth by a tube rotating together with the rotor. A connection of the inner material with the outer material is only inadequately ensured using a nozzle arrangement of this type.
Devices are known from EP-A-0 168 255 and EP-A-0 177 175 for co-extruding two materials, which extrude an inner material through a nozzle and an outer material with grainy particles contained therein through a funnel enclosing the nozzle, the materials being combined to form a strand. At its mouth, the funnel comprises sharp edges, so that the grainy particles in the outer material reach the surface. The mouth of the funnel may be toothed, so that the particles project from the surface. The composite strand is carried away by a conveyor belt. In this manner, a baking article can be produced from two materials having a linear, longitudinal shape with grainy particles on the surface.
U.S. Pat. No. 5,120,554 describes a free-standing nozzle head for extruding a dough material. On its circumference, the nozzle head has a plurality of nozzle arrangements, which are formed in each case by a double nozzle in order to produce filled baking articles. These double nozzles each comprise an inner nozzle, which is supplied by an individual feed duct, and an outer nozzle. The outer nozzles are supplied via a common cylindrical feed chamber through lateral ducts. The nozzle head allows for the simultaneous extrusion of a plurality of filled, straight strands.
A method and a device for producing twisted cereal products are known from U.S. Pat. No. 5,518,749 and WO 97/25881. A rotor, which extends through a chamber and opens out into an opening of the chamber, forms an inner nozzle, through which an inner material can be supplied. A second material can be supplied to the chamber through a side duct. Formed between the opening of the chamber and the rotor is an annular gap, through which the second material can emerge. The annular gap corresponds to an outer nozzle. When the inner nozzle rotates, a product is formed with a twisted outer material layer and a filling. In this respect, the twisting of the outer material layer is closely dependent upon the properties of the outer material, such as flow behaviour and viscosity, for example. The extruded cereal products do not therefore always have a sufficiently uniform shape.
It is the object of the invention to provide a nozzle arrangement, a nozzle holder and a device for extruding dough materials, by means of which it is possible to manufacture twisted or coiled baking articles with at least one outer material and with at least one inner material or filling with a high degree of shape accuracy.
This object is attained according to the invention by a nozzle arrangement described below. Accordingly, during extrusion the rotary movement of the outer nozzle is superimposed over the longitudinal movement of the extruded material in the inner nozzle, so that an externally coiled baking article with a filling is produced. In this respect, the materials flow together at the mouth of the inner nozzle. According to the invention, this mouth is set back behind the mouth of the outer nozzle in relation to the direction of flow of the material. On its path from the mouth of the inner nozzle to the mouth of the outer nozzle, the inner material is set in rotation by the outer material and is thereby compressed. In this manner, a secure bond between the inner and outer materials is obtained. In the resulting baking articles, the coupling of the outer material to the inner material is therefore improved.
As a result of the design of the mouth of the outer nozzle, during extrusion the material emerges through the substantially longitudinally oriented recesses, e.g. longitudinal grooves, and forms one or more coiled webs on the curved surface of the cylindrical baking article. The shape and number of the said web or webs can be varied to a wide degree by the shape and number of the recesses.
Particularly suitable for driving the nozzle holder is a traction gearing, more particularly a toothed belt drive, or a toothed wheel gearing with crossing axes, it being possible in a special construction to drive a plurality of nozzle holders simultaneously.
It is provided in a preferred embodiment of the invention that the nozzle holder(s) is/are arranged inclined at an angle xcex1 of approximately 25xc2x0 to the vertical. As a result of the inclined nozzle holder, the emerging material arrives at an angle on a support, for example a conveyor belt, and is therefore less deformed during the further movement than would be the case if the material were to emerge vertically.